package service

import (
	"axolotl/models"
	"axolotl/store"
	"fmt"
)

// NodeService is the single entry point for all node operations.
// All data-model integrity rules are enforced here; callers cannot produce
// invalid state by interacting with this interface alone.
//
// Every NodeService instance is bound to a specific user (see User()).
// GetNodeService returns an error when no user is configured.
type NodeService interface {
	// User returns the name/ID of the user this service instance acts on behalf of.
	User() string

	// Query
	GetByID(id string) (*models.Node, error)
	List(filter ListFilter) ([]*models.Node, error)

	// Lifecycle
	Add(input AddInput) (*models.Node, error)
	Update(id string, input UpdateInput) (*models.Node, error)
	Delete(id string) error

	// User management
	AddUser(name string) (*models.Node, error)
	ListUsers() ([]*models.Node, error)
}

// AddInput describes a new node to create.
// Tags may include special property tags (_type::, _status::, _prio::); the
// service applies defaults (type=issue, status=open for issues) and validates.
// Rels may include assignee, in_namespace, blocks, subtask, related, etc.;
// user and namespace targets are auto-created as needed.
type AddInput struct {
	Title   string
	Content string
	DueDate string
	Tags    []string
	Rels    []RelInput
}

// UpdateInput describes changes to apply to an existing node.
// Nil pointer fields mean "no change".
// Setting _status::done in AddTags is rejected when the node has open blockers.
// Adding assignee or in_namespace rels replaces the previous single target.
type UpdateInput struct {
	Title      *string
	Content    *string
	DueDate    *string // nil = no change; pointer to "" = clear due date
	AddTags    []string
	RemoveTags []string
	AddRels    []RelInput
	RemoveRels []RelInput
}

// ListFilter specifies which nodes to return. Empty slices are ignored.
// Tags are matched as exact tag values or prefixes (e.g. "_status::open").
// Rels are resolved to node IDs; a missing target returns no results.
type ListFilter struct {
	Tags []string
	Rels []RelInput
}

// RelInput is a typed, directed edge with a target that may be a name or node ID.
type RelInput struct {
	Type   models.RelType
	Target string // name or node ID; the service resolves names
}

func InitNodeService(path string) error {
	return store.InitSQLiteStore(path)
}

func GetNodeService(cfg Config) (NodeService, error) {
	user := cfg.GetUser()
	if user == "" {
		return nil, fmt.Errorf("no user configured: run 'ax user set <username>' first")
	}
	st, err := store.FindAndOpenSQLiteStore()
	if err != nil {
		return nil, err
	}
	return &nodeServiceImpl{store: st, userID: user}, nil
}